Cigarette filter element containing certain hexahydrotriazines for the selective removal of acrolein



United States Patent 3,349,779 CIGARETTE FILTER ELEMENT CONTAINING CERTAllN HEXAHYDROTRIAZINES FOR THE SELECTIVE REMOVAL OF ACROLEIN Ray E. Leonard and John E. Kiefer, Kingsport, Tenn., as-

signors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey N0 Drawing. Filed Aug. 26, 1965, Ser. No. 482,925 14 Claims. (Cl. 131266) This invention relates to chemical additives for use with tobacco smoke filters, and to smoking devices such as, for example, cigarettes which employ tobacco smoke filters containing such additives. More particularly, this invention concerns the addition of hexahydrotriazine additives to tobacco smoke filter elements for reducing the concentration of acrolein which passes therethrough when the tobacco is smoked.

Tobocco smoke, as is well known, consists of a gaseus or vapor phase in which are suspended liquid or semiliquid droplets and certain solid particles. It is also known that various compounds and materials that exist in these gaseous, liquid 'and solid phases of the tobacco smoke contribute nothing beneficial to the pleasant taste or aroma of the smoke. Thus much effort has been expanded in developing suitable methods and devices for removing these deleterious compounds and materials from tobacco smoke without at the same time affecting the pleasant flavor and aroma of the smoke. This concerted effort by the tobacco industry led to the development of the standard commercial cigarette filter which normally consists of a bundle of cellulosic fibers or convoluted crimped paper formed into a cylindrical plug. Such filters are designed to and do remove varying proportions of the droplets and solid particles passing through them thereby greatly reducing the amount of undesirable materials reaching the smokers mouth. This filtering action is accomplished by a combination of diffusional, impactive, and direct collision of the droplets with the filter material. Upon collision the droplets are retained in the filter by the surface attraction between the extremely small partitiles and the relatively large filter material.

However, these plug type filters per se generally are unable to remove many of the noxious vaporized components from the smoke stream by the processes of physical and chemical adsorption. Certain of these gaseous components are especially toxic and adversely affect the human tissues with which they come into contact. Acro: lein is one of these undesirable gases to be found in the smoke of burning tobacco. This specific gaseous component of tobacco smoke merits special attention, however, since it has been found to contribute to the inhibition of the action of the whiplike appendages or cells called cilia which line the trachea and bronchioles. These cells rhythmically beat to and fro, and by this action carry foreign bodies up and out of the respiratory tract thereby preventing such foreign particulate matter from accumulating in the respiratory system. When the activity of the cilia is inhibited by the acrolein in tobacco smoke, the smoke particles including any tar particles contained in the smoke will pass by the less active or quiescent cilia and collect in the lungs or other parts of the respiratory tract.

and silica gels. Such adsorbent-containing tobacco smoke 3,349,779 Patented Get. 31', 1967 filters are effective to some extent in removing ciliary depressants from the vapor phase of cigarette smoke, but their use has some definite disadvantages. For example, such adsorbent additives indiscriminately remove from the tobacco smoke not only certain obnoxious or "toxic components, but many other components as well which are necessary for maintaining the desired flavor and aroma of the smoke. In the case of activated carbon, which at the present time is the most commonly used adsorbent additive, the removal of these flavoring agents imparts an undesirable taste to the smoke that is commonly referred to as the carbon taste. Furthermore, since the adsorption of vapors by these materials is based on physical phenomena, which are in turn dependent upon temperature and pressure, many of the adsorbed vapors including those that are deleterious may later be released in concentrated quantities as the burning Zone of the cigarette approaches the filter during the smoking of the cigarette. If enough carbon is used in the filter to compensate for this deficiency, the cigarette becomes for all practical purposes, unsmokable.

Therefore, it is readily apparent that an improvement in the tobacco smoke filter art which would permit the substantial reduction or complete elimination of acrolein vapors from tobacco smoke without at the same time adversely affecting the flavor and aroma of the smoke would represent a substantial stride forward. Ideally this improvement should use a material and/or method that is inexpensive, reliable and commercially available. Furthermore, the filter should be capable of removing only the deleterious vapors found in tobacco smoke, and the vapors removed should be chemically reduced so that they will not be eluted at a later time due to a change in the filter structure or environment. The process whereby the filter is produced must also be compatiable with existing manufacturing equipment and capable of being performed at the speeds demanded by industry.

According to the present invention a convenient and effective method has been found by which a tobacco smoke filter can be constructed for the selective removal of acrolein vapors from tobacco smoke. This method consists of coating, dusting or otherwise dispersing selected hexahydrotriazines onto the filtering material from which the tobacco smoke filter element is formed. The acrolein vapor is reduced chemically to an inert material upon its contact with the hexahydrotriazines in the filter thereby preventing the acrolein from reaching the smokers mouth.

Therefore, an object of this invention is to provide a new and improved tobacco smoke filter unit.

Another object of this invention is to disclose a chemical additive for tobacco smoke filters which will substantially eliminate certain ciliary-depressant substances found in tobacco smoke.

Yet another object of this invention is to disclose a coated granular additive for use with a tobacco smoke filter which will chemically reduce the concentration of ciliary-depressants, such as acrolein, from the tobacco smoke passing through the filter.

'Still another object of this invention is to disclose a new tobacco smoke filter tow, and a method of manufacturing the same, which contains hexahydrotriazines capable of chemically reducing the acrolein vapors found in tobacco smoke to a harmless material.

A further object of this invention is to describe a cigarette filter having hexahydrotriazines therein for selectively removing acrolein vapors from tobacco smoke by a chemical technique.

A still further object of this invention is to describe a method and process of manufacturing a cigarette filter from a cellulose acetate tow which contains hexahydrotriazine additives capable of removing acrolein from tobacco smoke.

Yet another object of this invention is to describe a dual-type cigarette filter having a section of granules coated with at least one hexahydrotriazine that is capable of selectively removing acrolein from tobacco smoke.

These and further objects and advantages of this invention will be more apparent upon reference to the accompanying specification, specific working examples, and claims.

As set out hereinabove, this invention in its broadest aspects involves the use of certain hexahydrotriazines in tobacco smoke filters for selectively removing acrolein vapors from tobacco smoke. The hexahydrotriazines which have been found to be most elfective in the selective removal of acrolein vapors from the gaseous phase of tobacco smoke are (1) hexamethylenetetramine; (2) 1,3,S-tricyclohexyl hexahydro-s-triazine; (3) 1,3,5-triphenylhexa'hydro-s-triazine, or (4) derivatives as illustrated by the following general formula:

CH3 where R=any alkyl, aryl, and arylalkyl derivative.

Since the hexahydrotriazines act through physical contact to chemically reduce the acrolein vapor, it is very important that as much surface area of the hexahydrotriazines be exposed for contact with the acrolein vapor as possible. This desired surface exposure can be accomplished, for example, by adding the hexahydrotriazines to any general type of cigarette filtering material such as cellulose acetate tow, paper, cotton, polypropylene and polyethylene fibers, or any other suitable materials having large surface areas that are inert to the hexahydrotriazines and can be used as a carrier medium.

The hexhydrotriazine additives contemplated by this invention can be incorporated into the various carrier materials in any desirable manner. For example, solutions of the hexahydrotriazine additive in a suitable solvent, such as water, may be applied to the filter material by spraying, soaking, sprinkling or the like after which the solvent is driven otf as a vapor leaving the additive thoroughly incorporated within the material. The hexahydrotriazine additives may also be applied as a finely- -divided solid material through a dusting, shaking or dispersing medium of any suitable type which will uniformly disperse the additive over the filter. The incorporation of the additive may take place at any time prior to the final packaging of the tobacco smoke filter. In the case of cigarette filters, it may be incorporated before or after the binder material is sprayed onto the tow.

The hexahydrotriazines can also be dispersed in a plasticizer or other suitable bonding liquid as, for example, glyceryl triacetate (triacetin) and applied to the filtering material by any convenient method such as by spraying or rolling the triacetin suspension on the tow or other filtering materials. This desirable feature is rather unexpected since it was commonly believed in the tobacco industry that if a granular material of the hexahydrotriazine type were incorporated into a plasticizer or bonding material, the hexahydrotriazine would become ineffective for removing acrolein from tobacco smoke since the plasticizer would mask it from coming into contact with the smoke. This, however, does not occur. In fact, suitable size granules of the hexahydrotriazines can be mixed with selected types of spinning solutions, such as cellulose acetate dopes, and spun to give a filament that readily neutralizes the acrolein in tobacco smoke.

The hexahydrotriazines can also be utilized by themselves as one element in a dual-type cigarette filter. This can be accomplished by using hexahydrotriazines in the form of a powder, pellet or applied to the surface of some granular substance, such as cellulose acetate powders, as the middle portion of the dual filter. The front and back portions of the filter can be constructed from any suitable filtering material as, for example, cellulose acetate tow. The hexahydrotriazines may also be blended with or coated onto a suitable flake or granular thermosensitive bonding material of, for example, the polyolefin class and the granular additive so formed can be used not only as a means for removing acrolein vapors from tobacco smoke, but also as the bonding agent for a fibrous filter tow material. To bond such a fibrous filter tow material with a granular polyolefin that is either coated with or has a powdered hexahydrotriazine blended therewith, it is only necessary that the additive be applied to the fibrous filter and then heated to soften the thermoplastic particles thereby randomly fusing the fibers of the tow as it is compacted into a filter rod.

The amount of hexahydrotriazine additives in the final tow or filter product contemplated by this invention is rather small but somewhat critical. Generally speaking, desirable reduction of ciliary depressants can be obtained if the hexahydrotriazine additives are incorporated into the final tobacco product in amounts between 1 and 15 percent by weight (dry bases).

A further understanding of the invention will be had from a consideration of the following examples that may be used in actual commercial practice and are set forth to illustrate certain preferred embodiments.

Example 1 A -mm. length of 5 denier/filament (d./ f.) crimped cellulose acetate filter tow which had 10,000 filaments and weighed approximately 1 gram was spread out in a conventional manner to a width of about 15 inches. The tow was then passed under a spray nozzle where a solution consisting of 50 percent by weight of hexarnethylenetetramine suspended in an equal weight of water was sprayed onto the tow. The tow containing the 50-50 w./w. aqueous solution of hexamethylenetetramine was then dried to drive off the water solvent thereby leaving a uniform coating of hexarnethylenetetramine over the cellulose acetate fibers. The amount of the 50-50 w./w. aqueous solution being sprayed onto the spread tow was set so that the tow contained 12 percent of hexamethylenetetramine based on the dry weight of the tow.

The hexamethylenetetramine coated tow was then sprayed with triacetin, compacted, wrapped with a paper to form a filter rod with a circumference of 25-mm., and allowed to stand until firm. The triacetin bonds the tow making a rigid rod and leaving the hexamethylenetetramine evenly distributed throughout the tow thereby taking full advantage of the large surface area which the tow filtering material provides. This is important since the surface area of the tow filtering material is the vehicle which provides the contact necessary for the hexamethylenetetramine to remove the acrolein vapor in the tobacco smoke efficiently. After the rod became firm, it was cut into 20-mm. segments which contained 12 percent hexamethylenetetramine based on the dry weight of the tow. These 20-mm. segments were attached to regular kingsize cigarettes and ZO-mm. lengths of the new filter tipped cigarettes were then cut off so that they would have the same length or tobacco content as a commercial king-size filter cigarette.

The filter tipped cigarettes were smoked with an automatic smoking device and the vapors which passed through the filters were collected and analyzed by gas chromatography. Table 1 lists the results obtained on the hexamethylenetetramine filter. Also listed are the results obtained from a regular or unfiltered king-size cigarette and a king-size cigarette having a 20-mm. cellulose acetate filter (5 d./f., 10,000 filaments) without any hexamethylenetetramine added thereto.

Table 1 pg. acrolein found in smoke from one cigarette Example 2 A 170-mm. length of 5 d./f. crimped cellulose acetate filter tow which had 10,000 filaments and weighed approximately 1 gram was spread out in a conventional manner to a width of about 15 inches. The spread tow was then sprayed with triacetin until the fibers of the tow contained 7 percent triacetin based on the weight of dry tow. 1,3,S-triphenylhexahydro-s-triazine was then dusted onto the triacetin treated tow until 5.5 percent based on the weight of dry tow had been added. The tow was then compacted, Wrapped with a paper to form a filter rod with a circumference of 25-mm., and allowed to stand until firm. The triacetin cured the tow thus making a rigid rod and leaving the 1,3,S-triphenylhexahydro-s-triazine evenly distributed throughout the tow for efficiently removing any acrolein vapor it comes into contact with. After the rod became firm it was cut into 20-min. segments which were attached to regular king-sized cigarettes. A 20-mm. length of the king-size cigarette was then cut ofl to retain the length of a commercial king-size cigarette.

The filter tipped cigarettes were smoked with an automatic smoking device and the vapors which passed through the filters were collected and analyzed by gas chromatography. Table 2 lists the results obtained on the filter containing the 1,3,S-triphenylhexahydro-s-triazine additive. Also listed are the results obtained from a kingsize unfiltered cigarette and a king-size cigarette having a ZO-mm. cellulose acetate filter (5 d./f., 10,000 filaments) without any 1,3,S-triphenylhexahydro-s-triazine added thereto.

Table 2 ,ug. acrolein found in smoke from one cigarette- Without filter 90 With a cellulose acetate filter 85 With a l,3,S-triphenylhexahydro-s-triazine treated cellulose acetate filter 56 From the foregoing description it is readily apparent that the hexahydrotriazine containing tobacco smoke tow and filter of this invention offers numerous detoXicating advantages over-those filters previously known and used in the cigarette industry. For example, not only is the filter a highly selective one which is capable of removing substantial amounts of the gas acrolein found in tobacco smoke as it moves through the interstices of the filters, but the acrolein removed by contacting the hexahydrotriazine is neutralized or reduced to an inactive and harmless byproduct which cannot later be eluted from the filter. Furthermore, the fact that the hexahydrotriazines can be mixed or blended with various liquid or solid bonding materials for the filter tow, as well as with the spinning dopes themselves, substantially eliminates the masking, sifting-out and house-cleaning problems heretofore so commonly encountered where additives are used. The method and ease with which the hexahydrotriazine additives can be evenly dispersed throughout a tobacco smoke filter also alleviates the need for practically all the special equipment, processing steps and skilled personnel that has heretofore been required to produce a filter tow having an additive therein. Thus the cost of producing the tow, as well as the filter units themselves, by the method and with the materials of this invention is substantially reduced over other comparable commercial products.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

1. As a new article of manufacture, a tobacco smoke filter element containing a finely-divided hexahydrotriazinc which will react with and neutralize substantially all acrolein in the tobacco smoke passing through said filter element.

2. As a new article of manufacture, a tobacco smoke filter element containing an additive of a hexahydrotriazine which will react with and neutralize substantially all acrolein in the tobacco smoke passing through said filter element, and a bonding material for said filter element.

3. As a new article of manufacture, a tobacco smoke filter element containing between 1 and 15 percent by weight of a hexahydrotriazine additive which will react with and neutralize substantially all acrolein in the tobacco smoke passing through said filter element.

4. As a new article of manufacture, a tobacco smoke filter element of the fibrous type containing between 1 and 15 percent by weight of a hexahydrotriazine coated thereon which will react with and neutralize substantially all acrolein in the tobacco smoke passing through said filter element.

5. A tobacco smoke filter tow adapted to be formed into a tobacco smoke filter element comprising a carrier material having a hexahydrotriazine material associated there with which will react upon contact with and neutralize the acrolein found in tobacco smoke.

6. A tobacco smoke filter tow according to claim 5 wherein said hexahydrotriazine material is coated on said carrier material.

7. A tobacco smoke filter tow according to claim 5 wherein said hexahydrotriazine material is in a finelydivided form evenly distributed throughout said carrier material.

8. A tobacco smoke filter tow according to claim 5 wherein said carrier material is continuous fibers of cellulose acetate.

9. A tobacco smoke filter for tain ciliary depressants from interstices formed in said filter selectively removing certobacco smoke comprising through which the tobacco hydrotriazine material is selected from a compound of the formula wherein R is an alkyl, aryl or arylalkyl derivative.

11. A tobacco smoke filter of claim 9 wherein the heXahydrotriazine material is selected from the group consisting of hexamethylenetetramine; 1,3,5-tricycloheXylhex-ahydro-s-triazine; and 1,3,S-triphenylhexahydro-s-triazine.

12. A rod-shaped cigarette filter element adapted for selectively removing acrolein from tobacco smoke which comprises compacted substantially horizontally aligned 7 ilaments having as additives thereon a compound of the formula R l H2? (III-I; R-N NR CH2 wherein R is any alkyl, aryl or arylalkyl derivative.

13. A rod-shaped cigarette filter element adapted for selectively removing acrolein from tobacco smoke which comprises compacted substantially horizontally aligned filaments having as additives thereon a compound selected 8 from the group consisting of hexamethylenetetramine; 1,3,5'tricyclohexylhe-xahydro-s-triazine; and 1,3,5-triphenylhexahydro-s-triazine.

14. A rod-shaped cigarette filter according to claim 13 5 wherein said filaments are cellulose acetate.

References Cited UNITED STATES PATENTS 12/1922 Herz 260-248 X Schreus et a1 13l267 X 

1. AS A NEW ARTICLE MANUFACTURE, A TOBACCO SMOKE FILTER ELEMENT CONTAINING A FINELY-DIVIDED HEXAHYDROTRIAZINE WHICH WILL REACT WITH AND NEUTRALIZE SUBSTANTIALLY ALL ACROLEIN IN THE TOBACCO SMOKE PASSING THROUGH SAID FILTER ELEMENT. 